TWI584951B - A heat-sealing film and a cover tape for packaging electronic components - Google Patents

Description

Heat sealing film and cover tape for packaging electronic components

The present invention relates to a heat seal film and a cover tape which are obtained from the heat seal film and which are heat sealable to a plastic carrier tape having a fan-shaped distribution pit therein, the tape carrier having the following functional package One of the following: When storing, transporting, or mounting electronic components, the electronic components are protected from contamination, and the electronic components are configured and removed for assembly on an electronic circuit substrate.

Recently, surface mount electronic components (such as ICs, transistors, diodes, capacitors, piezoelectric element resistors, and the like) are packaged into a plastic carrier tape in which embossed molding pits are sequentially formed, and electronic components can be received. And in the package formed by the cover tape of the carrier tape, and then supplied. After the cover tape is peeled off, the packaged electronic components are automatically taken out from the package and then surface mounted on the electronic circuit substrate.

The strength of the self-loading tape peeling cover tape is referred to as "peel strength", and when the strength is too low, there is a problem that the cover tape is detached during transport packaging and the electronic component package is detached.

On the other hand, when the strength is too high, the following phenomenon will occur: the carrier tape vibrates when the cover tape is peeled off and the electronic component jumps out of the storage pit before it is about to be installed, that is, causes a jitter failure. In addition, it is necessary to maintain the peel strength of a certain cover tape within a certain range. If the change in peel strength is too large, it is difficult to stably peel the cover tape by using a mounting machine.

Antistatic property is another key property, because static electricity can damage electronic bills. Yuan, and can cause certain difficulties in the process. The transparency of the cover tape is also important because of the need to check the status of the electronic components through the cover tape. In addition, the cover tape should not contaminate electronic components.

Currently, the mechanisms for covering self-loading tape stripping on the market are classified into the following three categories: interface peeling type, transfer peeling type, and cohesive failure type. The type of interface peeling refers to the type in which the cover tape and the carrier tape are peeled off from each other on the sealing surface, the transfer peeling type refers to the type in which the bonding layer itself is transferred to the carrier tape during peeling, and the type of cohesive failure refers to a layer different from the bonding layer or The bonding layer itself (both of which are hereinafter referred to as cohesive failure layers) is broken to cause a type of peeling.

Each of these types has advantages and disadvantages; however, the interface peeling type is often affected by the shape, material and properties of the carrier tape when compared only for the state of peeling the seal to the cover tape of the carrier tape. This is because the sealing surface and the peeling surface are the same, and thus the peel strength tends to become unstable.

In the case of a transfer release type, the bonding layer must be a film in terms of mechanism and must use a so-called heat seal spray paint. Therefore, the peel strength tends to become susceptible to the sealing temperature, and thus it is difficult to obtain a sealing condition for a suitable peel strength.

In the case of a cohesive failure type, the sealing surface and the peeling layer are different, and thus the peel strength is less dependent on the sealing conditions. Also, the cohesive failure type has the significant advantage that the peel strength is not affected by the shape, material and properties of the carrier tape. However, in some cases, during the peeling, the cohesive failure layer is affected by the layer (including the bonding layer) other than the cohesive failure layer and the interface is peeled off without causing cohesive failure.

Also, it is difficult to determine the position at which the cohesive failure layer is broken, and thus the cohesive failure layer is maintained on the surface of the carrier tape during peeling and a state in which the contents cannot be taken out is generated.

The cohesive failure layer itself is designed to be easily broken, and thus in many cases it is a mixture of a plurality of resins which are difficult to be miscible with each other and which are not uniformly mixed. This results in a reduction in the transparency of the cover tape and in some cases certain disadvantages due to the binder. Also, in such applications, in some cases, the resin mixture contains a resin having poor heat resistance. For these reasons, in many cases, cohesive or degradation products are produced during formation of the cohesive failure layer and productivity is reduced.

Therefore, there is a need to develop a transparent cover tape having stable peel strength, excellent antistatic properties, and no contamination of electronic components.

The object of the present invention is to develop a heat seal film which can be cut into a cover tape, has stable peel strength, good antistatic property, does not pollute electronic components and has a transparent appearance.

Another object of the present invention is to provide a cohesive failure or transfer release type cover tape made from a heat seal film.

According to the present invention, there is provided a heat seal film encapsulating an electronic component, comprising: a base layer; at least one intermediate layer provided on the base layer and comprising a mixture comprising 100% by weight of the total weight of the intermediate layer : 5 to 70% by weight of a vinyl acetate copolymer, wherein the unit derived from vinyl acetate accounts for more than 10 mol% of the copolymer; 20 to 90% by weight of a styrene-butadiene copolymer; and 0 to 40% by weight of a conductive polymer; and at least one heat seal layer provided on a surface of the intermediate layer opposite to the substrate layer.

The present invention further provides a cover tape heat-sealed to a carrier tape comprising an electronic component, the cover tape comprising: a base layer; an intermediate layer disposed on the base layer; and a heat seal layer disposed on the intermediate layer, the cover tape Having an average optical transmittance of at least 75%, an optical haze of no more than about 50%, and a surface resistivity of no more than about 1 x 10 ¹¹ ; such that when the cover tape is heat sealed to the carrier tape to form an article, the cover tape is The average peel strength of the carrier tape is at least 20 gf/mm, and the peel strength is reduced by no more than about 10% when the article experiences a temperature of not less than about 50 ° C and a relative humidity of not less than about 90% for at least 5 days.

The antistatic heat seal film of the present invention has excellent static dissipative properties, good optical properties, good mechanical properties, and excellent heat sealing properties to the surface of polycarbonate, polystyrene, polypropylene or the like. The heat-sensitive cover tape obtained from the heat-sealable film of the present invention has many advantages such as permanent antistatic property on both sides, high light transmittance, low haze, stable peeling force with carrier tape, and excellent sealing aging property. . In the case of using a heat-sensitive cover tape, the adhesive face after aging at high temperature and high humidity does not easily adhere to the surface of the carrier tape, and the problem of the tape opening cannot be produced after the carrier tape is sealed with the heat-sensitive cover tape. After the cover tape obtained by using the tape-sealed self-heat sealing film, the adhesive layer remains on the support tape after peeling off, and the adhesive layer can be combined with Functional layer separation. Compared with the case of the cover tape on the market, in which the adhesive layer is separated from the carrier layer, the process is excellently controlled by the surface of the functional layer and the adhesive layer, and the coverage obtained by the method can be ensured. Excellent controllable peeling effect with product. Further, the surface roughness of the carrier tape is relatively high, and if the adhesive layer is separated from the carrier layer after peeling, the stability of the peeling force is poor.

In the present invention, the term "heat-sensitive adhesive" means a heat-sealable polymer resin unless otherwise specified. The term "additional cationic antistatic coating" means a coating having antistatic properties obtained by adding a cationic antistatic agent to a coating.

The present invention provides a heat seal film for packaging electronic components, comprising: a base layer; at least one intermediate layer provided on the base layer and comprising a mixture comprising, in terms of 100% by weight of the total weight of the intermediate layer: 5 - 70% by weight of a vinyl acetate copolymer, wherein units derived from vinyl acetate account for more than 10 mol% of the copolymer; 20 to 90% by weight of a styrene-butadiene copolymer; and 0-40 weight And a conductive polymer; and at least one heat seal layer provided on a surface of the intermediate layer opposite to the base layer.

The base layer is primarily used to provide mechanical strength to the film. In the present invention, a substrate layer which is not particularly limited to the substrate layer and which is generally used for producing a heat seal film can be used in the present invention. Preferably, the base layer is selected from the group consisting of biaxially stretched polyester, polyolefin Hydrocarbon or nylon (nylon). Preferably, the base layer has a thickness of from about 10 to 30 μm. The film preferably has an optical transmittance of not less than 85% and a tensile strength of not less than 50 MPa.

The intermediate layer used in the heat seal film of the present invention is relatively soft and electrically conductive, and may be composed of one layer or a plurality of layers. The polyethylene suitable for the intermediate layer is preferably a linear low density polyethylene (LLDPE), more preferably having a weight average molecular weight of more than 100,000 and a melt index (test conditions of 190 ° C, 2.16 kg, ASTM D1238) of 1-100. G/10 minute linear low density polyethylene. Suitable polyethylenes are, for example, LLDPE (1002-YB) available from Exxon Mobil. The content of polyethylene in the intermediate layer is from 0 to 60% by weight, preferably from 10 to 60%, more preferably from 20 to 60% and most preferably from 50 to 60%.

In the intermediate layer, a vinyl acetate copolymer-based vinyl acetate-derived unit has a molar percentage of at least 10%, preferably more than 15%, and most preferably more than 20%. Suitable co-monomers are preferably selected from the group consisting of olefins, more preferably from ethylene. The melt index of the suitable vinyl acetate copolymer (test conditions of 190 ° C, 2.16 kg, ASTM D1238) is preferably from 1 to 250 g/10 min, more preferably from 1 to 100 g/10 min, and most preferably from 2 to 2 50 g/10 minutes. The content of the vinyl acetate copolymer in the intermediate layer is from 5 to 70% by weight, preferably from 5 to 50%, more preferably from 10 to 60%, still more preferably from 10 to 40%, still more preferably from 20 to 40%. And optimally 20-30%.

The styrene-butadiene copolymer suitable for the intermediate layer is preferably a styrene-derived unit of 50 mol% or more, more preferably 60 mol% or more, and most preferably 70 mol% or more of the total copolymer unit. Block copolymer. Preferably, the weight average molecular weight of the suitable styrene-butadiene copolymer is preferably 20,000 to 500000, more preferably 40,000 to 300,000, and most preferably 50,000 to 150,000, and the molecular weight distribution is preferably 1-2. The styrene-butadiene copolymer accounts for 20-90%, preferably 30-70%, of the total weight of the intermediate layer.

The intermediate layer preferably has a thickness of 10 to 50 μm and its surface can be electrically conductive by adding a conductive polymer as needed. For example, the surface resistivity may be less than 1 × 10 ¹¹ ohms / □, more preferably less than 1 × 10 ¹⁰ ohms / □, and most preferably less than 1 × 10 ⁹ ohms / □. Suitable electrically conductive polymers include, but are not limited to, polyacetylene, polypyrrole, polythiophene, polyaniline, polyether decylamine or polyester guanamine based intrinsic antistatic polymer or the like, or combinations thereof.

In the case where a separate polyethylene layer is not provided, an adhesive layer may be provided between the intermediate layer and the base layer as needed. In the case where a separate polyethylene layer is provided, an adhesive layer is provided between the polyethylene layer and the substrate layer as needed. The adhesive layer can be a conventional curable polyurethane adhesive.

According to some embodiments, the intermediate layer is formed primarily by blending an ethylene-vinyl acetate copolymer, a styrene-butadiene block copolymer, and an amount of an intrinsically conductive or antistatic polymer using an extruder. Polymer alloy. The surface resistivity of the layer is preferably from 1 × 10 ^{6 to} 1 × 10 ¹⁴ ohms / □. The ethylene type copolymer used in the intermediate layer may be poly(vinyl acetate). The poly(vinyl acetate) has a VA chain segment content of more than 10% and accounts for 10 to 60% by weight of the polymer alloy in the entire functional layer. The styrene-butadiene copolymer to be used has a polystyrene chain segment content of more than 50%. The block copolymer has a weight average molecular weight of 20,000 to 500,000 and a molecular weight distribution of 1-2. The copolymer comprises from 30 to 90% by weight of the polymer alloy in the entire functional layer. The intrinsically conductive or antistatic polymer to be used may be ICP (Intrinsically Conductive Polymer) or IDP (Intrinsically Dissipative Polymer), including polyacetylene, polypyrrole, polythiophene, polyaniline, polyether-based amine or poly-based An essential antistatic polymer of ester amide or the like, or a combination thereof, which comprises from 0 to 40% by weight of the polymer alloy in the entire functional layer.

A heat seal layer (also referred to as "thermosensitive adhesive layer" in the present invention) is provided on the surface of the intermediate layer opposite to the base layer. The heat seal layer may be composed of one or a plurality of layers of materials and may or may not be electrically conductive as desired. Preferably, the heat seal layer is composed of a material selected from the group consisting of polyacrylates or copolymers thereof and the glass transition temperature of the polymer should be higher than 30 ° C, more preferably higher than 60 ° C, and most preferably 70-90 ° C. . If necessary, if a conductive or antistatic polymer is not added to the intermediate layer, a certain amount of conductive particles may be added to the heat seal layer. For example, the heat seal layer may be added with a certain amount of conductive fill. A coating of a polyacrylate or a copolymer thereof. The heat seal layer may have a thickness of from 0.01 to 10 μm and a surface resistivity of from 1 × 10 ^{7 to} 1 × 10 ¹² ohms / □, more preferably from 1 × 10 ^{7 to} 1 × 10 ¹¹ ohms / □. The conductive filler may be a nano oxide such as titanium oxide, hafnium oxide, aluminum oxide, zinc oxide, tin oxide, antimony oxide, indium tin oxide or the like. The conductive filler may also be a carbon nanotube, a carbon powder, a metal powder or the like. The conductive filler particles added to the layer preferably constitute from 0 to 60% by weight, more preferably from 0 to 30% by weight based on the entire heat-sensitive adhesive layer. The polyacrylate or copolymer thereof to be used in the heat seal layer has a preferred glass transition temperature of 30 to 90 ° C and a preferred heat activation temperature of 90 ° C or higher.

An antistatic coating can be applied to the surface of the substrate layer as needed. The dry film thickness of the antistatic coating can be, for example, from 0.01 to 2 microns, preferably from 0.05 to 1 micron, and most preferably from 0.1 to 0.8 microns. The surface resistivity of the antistatic coating layer may be 1 × 10 ⁶ to 1 × 10 ¹² ohms / □, more preferably 1 × 10 ⁹ to 1 × 10 ¹¹ ohms / □. The antistatic coating on the substrate layer can be achieved by a gravure coating procedure. Even in the case where the ambient humidity is 50%, the surface resistivity of the antistatic coating is not higher than 1 × 10 ¹² ohms / □. The coating may be an additive type cationic antistatic coating or a polymer graft type cationic antistatic coating, and it may also be a polymer coating having a relatively good temperature resistance to which a conductive filler is added. The electrically conductive filler can be selected from the group consisting of metal oxides, carbon nanotubes or other electrically conductive particles.

1 is a cross-sectional view of a cover tape in accordance with an embodiment of the present invention. The 2 series is a base layer having a thickness of about 10-30 microns and is primarily used to provide mechanical strength to the film. The surface of the base layer 2 is coated with an antistatic coating 1 having a dried film thickness of 0.01 to 2 μm and a surface resistivity of 1 × 10 ⁶ to 1 × 10 ¹² Ω / □. A functional layer 3 having a conductive surface (in the present invention, a functional layer means an intermediate layer) is used to cast a surface of the base layer 2 opposite to the antistatic coating 1. The functional layer 3 has a thickness of 10 to 50 μm and a surface resistivity of 1 × 10 ⁵ to 1 × 10 ¹⁰ Ω / □. The surface of the functional layer 3 opposite to the base layer 2 is subjected to a heat-sensitive adhesive layer 4 having a thickness of 0.01 to 10 μm and a surface resistivity of 1 × 10 ⁵ to 1 × 10 ¹² ohms / □ (in the present invention, a heat-sensitive adhesive) The layer is equivalent to the heat seal layer) coating.

In the structure of Fig. 1, the base layer 2 may be a plastic film having a certain mechanical strength selected from the group consisting of biaxially stretched polyester, polyolefin or nylon. The film has an optical transmittance of not less than 85% and a tensile strength of not less than 50 MPa. The antistatic coating 1 on the substrate layer is achieved by a gravure coating process. When the ambient humidity is 50%, the surface resistivity of the surface is not higher than 1 × 10 ¹² ohms / □. The coating may be an additive type cationic antistatic coating or a polymer graft type cationic antistatic coating, and it may also be a polymer coating having a relatively good temperature resistance to which a conductive filler is added. The electrically conductive filler can be selected from the group consisting of metal oxides, carbon nanotubes or other electrically conductive particles. The functional layer 3 is mainly a polymer alloy formed by blending an extruded ethylene copolymer, a styrene-butadiene block copolymer, and a certain amount of an intrinsically conductive or antistatic polymer using an extruder. The surface resistivity of this layer was 1 × 10 ⁶ - 1 × 10 ¹⁴ ohm / □. The heat-sensitive adhesive layer 4 is mainly a coating of a polyacrylate or a copolymer thereof to which a certain amount of conductive particles is added, and has a thickness of 0.01 to 10 μm and a surface resistance of 1 × 10 ^{6 to} 1 × 10 ¹² ohms / □. rate.

The ethylene type copolymer used in the functional layer 3 may be poly(vinyl acetate). The poly(vinyl acetate) has a VA segment content of more than 10% and accounts for 10 to 60% by weight of the polymer alloy in the entire functional layer 3. The styrene-butadiene copolymer to be used has a polystyrene chain segment content of more than 50%. The block copolymer has a weight average molecular weight of 20,000 to 500,000 and a molecular weight distribution of 1-2. The copolymer comprises from 30 to 90% by weight of the polymer alloy in the entire functional layer. The intrinsically conductive or antistatic polymer to be used may be ICP or IDP, comprising polyacetylene, polypyrrole, polythiophene, polyaniline, polyether decylamine or polyester guanamine based antistatic polymer or the like or Combination, which accounts for 0-40 wt% of the polymer alloy in the entire functional layer.

The polyacrylate or copolymer thereof to be used in the heat-sensitive adhesive layer 4 has a glass transition temperature of 30 to 90 ° C and a heat activation temperature of 90 ° C or higher. The conductive filler particles added to the layer accounted for 0-60 wt% of the entire adhesive layer. The conductive filler may be a nano oxide, for example, titanium dioxide, cerium oxide, aluminum oxide, zinc oxide, tin oxide, antimony oxide, indium tin oxide or And so on. The conductive filler may also be a carbon nanotube, a carbon powder, a metal powder or the like.

Figure 2 is a cross-sectional view of another cover tape of the present invention. The surface of the base layer 2 is coated with an antistatic coating 1. The surface of the base layer 2 opposite to the antistatic coating 1 is applied via the adhesive layer 5 via the functional layer 3. The surface of the functional layer 3 opposite to the adhesive layer 5 is coated with the heat-sensitive adhesive layer 4.

Figure 3 is a cross-sectional view of another cover tape of the present invention. The surface of the base layer 2 is coated with an antistatic coating 1. The polyethylene layer 6 and the functional layer 3 (the polyethylene layer 6 constitutes a part of the functional layer 3) are formed by co-extrusion blow molding. The surface of the polyethylene layer 6 is combined with the base layer 2 via the adhesive layer 5. The surface of the functional layer 3 opposite to the polyethylene layer 6 is coated with the heat-sensitive adhesive layer 4.

The present invention further provides a cover tape heat-sealed to a carrier tape comprising an electronic component, the cover tape comprising: a base layer; an intermediate layer disposed on the base layer; and a heat seal layer disposed on the intermediate layer, the cover tape Having an average optical transmittance of at least 75%, an optical haze of no more than about 50%, and a surface resistivity of no more than about 1 x 10 ¹¹ ; such that when the cover tape is heat sealed to the carrier tape to form an article, the cover tape is The average peel strength of the carrier tape is at least 20 gf/mm, and the peel strength is reduced by no more than about 10% when the article is subjected to a temperature of not less than about 50 ° C and a relative humidity of not less than about 90% for at least 5 days.

The heat-sensitive cover tape of the present invention has many advantages such as permanent antistatic properties on both sides, high light transmittance, low haze, stable peeling force with a carrier tape, and excellent sealing aging properties. In the case of using a heat-sensitive cover tape, The adhesive surface after aging at high temperature and high humidity does not easily adhere to the surface of the carrier tape, and the problem of the tape opening cannot be produced after the carrier tape is sealed with the heat-sensitive cover tape. After the cover tape obtained by the carrier tape sealing self-heat sealing film is used, the adhesive layer remains on the support tape after peeling off, and the adhesive layer can be separated from the functional layer. Compared with the case of the cover tape on the market (where the adhesive layer is separated from the carrier layer, because the control layer is used to control the surface of the functional layer and the adhesive formulation well), the method can be ensured. Covers the stable peeling effect of the tape product. In addition, the surface roughness of the carrier tape is relatively high and the different carrier tapes have different surface roughness. If the adhesive layer is separated from the carrier layer after peeling, the stability of the peeling force is poor.

The invention is explained in more detail below by way of examples. It should be noted that the examples are in no way intended to limit the invention and the scope of the invention is determined by the scope of the appended claims. In the present invention, unless otherwise specified, all parts, percentages, contents, ratios are by weight, all temperatures are in degrees Celsius, and all values having unspecified units are most commonly used in the technical field. Unit count.

Instance

testing method:

Surface resistivity: Tested according to the ESD S11.11 standard test method under certain temperature and humidity conditions:

After placing the resistivity meter on the surface of the object to be measured, adjust the switch to the desired voltage position (10 V or 100 V) and press the test button with a pressure of approximately 5 lbs. The LCD screen will then display the measured surface resistivity. The unit of surface resistivity is ohm/□.

Optical Transmittance and Haze: This was measured by a haze meter HM-150.

Peeling force at 180°: The 5.4 mm wide cover tape and the 8 mm wide carrier tape were sealed by a heat sealing machine at 160 °C. Then, the peel force at 180° was measured by the peel force tester PT-45.

Aging test for peel force at 180°: A 5.4 mm wide cover tape and a 8 mm wide carrier tape were sealed at 160 ° C by a heat sealing machine. Then, the peeling force at 180° was measured by the peeling force tester PT-45; the sample was placed in an aging chamber of 52° C./95 rh%, and after aging for 5 days, the sample was taken out and subjected to a peeling force test. .

Anti-adhesion aging test at 60 ° C: The test specimen is adhered to the surface of the polycarbonate sheet and the sides thereof are fixed by an adhesive tape. The obtained sample was placed in an aging tank at 60 °C. After a certain period of time, the sample was taken out and it was observed whether or not adhesion occurred on the surfaces of the heat seal film and the polycarbonate sheet.

Example 1:

Preparation of functional layer materials:

67.5 kg of styrene-butadiene block copolymer (CHI MEI, PB-5903), 37.5 kg of poly(vinyl acetate) (HyunDai, VA60), 45 kg of intrinsic antistatic polymer (IDP: PolyNova PNC300R-M And 0.6 kg of antioxidant A5 (Jinhai Albemarle, Shanghai Jinhai Albemarle Fine Chemicals Co., Ltd.) were uniformly stirred and melt-mixed at 180 ° C, and then cooled and granulated for further use.

Preparation of heat sealing film and cover tape:

1. Preparation of a 16 μm thick single-sided corona discharge treated biaxially stretched polyester film. The surface of the corona discharge treatment was coated with a polyurethane-based undercoat layer having a thickness of about 0.2 μm, and then baked in an oven. At the same time, the polymer alloy prepared for the functional layer was melt-coated on the undercoat-coated polyester film, and then the obtained product was cooled and wound. The functional layer has a thickness of 30 μm and a surface resistivity of 1 × 10 ⁹ Ω/□.

2. 2 kg of polyacrylate copolymer (DSM, glass transition temperature of 42 ° C) powder was dissolved in 16 kg of ethyl acetate solvent with stirring, and then 2 kg of toluene was added and further stirred for 5 minutes for Further application. The solid content of the acrylic resin in the solution was 10%. The solution was applied to the surface having the functional layer and the obtained product was dried in an oven to remove the solvent and to wind it. The acrylic resin layer is a heat-sensitive adhesive layer having a thickness of about 1 μm. The surface of the heat-sensitive adhesive layer has a surface resistivity of 1 × 10 ¹⁰ Ω/□.

3. Apply an antistatic coating solution (K104A-2, Qingdao Trade Import and Export Co., Ltd.) having a solid content of 5% to the PET surface of the heat seal film opposite to the functional layer, and bake on the oven to Used for curing. The antistatic coating has a dry film thickness of 0.2 μm and a surface resistivity of 1 × 10 ¹¹ Ω/□ under normal temperature and normal humidity.

For the obtained heat seal film, the optical transmittance was 85%, the haze value was 10%, and the surface resistivity on the surface of the heat-sensitive adhesive was 1 × 10 ¹⁰ Ω/□, and the surface on the other surface. The resistivity was 1 × 10 ¹¹ ohms / □. The cover tape obtained by sealing the heat-sealing film at 170 ° C using a carrier tape had an average peeling force of 50 g and a peeling force fluctuation range of about 20 g. When the cover tape and the carrier tape are peeled off, the heat seal layer at the sealing position is completely retained on the carrier tape, and a small amount of the functional layer also resides on the carrier tape, so that the peeling is substantially peeled off due to the cohesive force of the functional layer. After aging for one week at 52 ° C / 95 rh%, the average value of the peeling force and the fluctuation range of the peeling force were substantially unchanged.

Example 2:

Preparation of functional layer materials:

67.5 kg of styrene-butadiene block copolymer (CHI MEI, PB-5903), 37.5 kg of poly(vinyl acetate) (HyunDai, VA60), 45 kg of intrinsic antistatic polymer (IDP: PolyNova PNC300R-M And 0.6 kg of antioxidant A5 (Jinhai Albemarle, Shanghai Jinhai Albemarle Fine Chemicals Co., Ltd.) were uniformly stirred and melt-mixed at 180 ° C, and then cooled and granulated for further use.

Preparation of heat sealing film and cover tape:

1. Preparation of a 16 μm thick single-sided corona discharge treated biaxially stretched polyester film. The surface of the corona discharge treatment was coated with a polyurethane-based undercoat layer having a thickness of about 0.2 μm, and then baked in an oven. At the same time, the polymer alloy obtained by the functional layer is melt-coated on the undercoat-coated polyester film, and then the obtained product is cooled and wound. The functional layer has a thickness of 30 μm and a surface resistivity of 1 × 10 ⁹ Ω/□.

2. 2 kg of polyacrylate copolymer (3M, glass transition temperature of 80 ° C) powder was dissolved in 16 kg of ethyl acetate solvent with stirring, and then 2 kg of toluene was added, and further stirred for 5 minutes for Further application. The solid content of the acrylic resin in the solution was 10%. The solution was applied to the surface having the functional layer and the obtained product was dried in an oven to remove the solvent and wound up. The acrylic resin layer is a heat-sensitive adhesive layer having a thickness of about 1 μm. The surface of the heat-sensitive adhesive layer has a surface resistivity of 1 × 10 ¹⁰ Ω/□.

3. Apply an antistatic coating solution (K104A-2, Qingdao Trade Import and Export Co., Ltd.) with a solid content of 5% on the PET surface of the heat seal film opposite to the functional layer, and bake on the oven to Used for curing. The antistatic coating has a dry film thickness of 0.2 μm and a surface resistivity of 1 × 10 ¹¹ Ω/□ under normal temperature and normal humidity.

For the obtained heat seal film, the optical transmittance was 85%, the haze value was 10%, and the surface resistivity on the surface of the heat-sensitive adhesive was 1 × 10 ¹⁰ Ω/□, and the surface on the other surface. The resistivity was 1 × 10 ¹¹ ohms / □. The cover tape obtained by sealing the heat-sealing film at 170 ° C using a carrier tape had an average peeling force of 50 g and a peeling force fluctuation range of about 20 g. When the cover tape and the carrier tape are peeled off, the heat seal layer at the sealing position is completely retained on the carrier tape, and a small amount of the functional layer also resides on the carrier tape, so that the peeling is substantially peeled off due to the cohesive force of the functional layer. After aging for one week at 52 ° C / 95 rh%, the average value of the peeling force and the fluctuation range of the peeling force were substantially unchanged.

Example 3:

Preparation of functional layer materials:

80 kg of styrene-butadiene block copolymer (CHI MEI, PB-5903), 20 kg of poly(vinyl acetate) (HyunDai, VA60), and 0.4 kg of antioxidant A5 (Jinhai Albemarle, Shanghai Jinhai Albemarle Fine Chemicals Co., Ltd.) was uniformly stirred and melt-mixed at 180 ° C, and then cooled and granulated for further use.

Preparation of heat sealing film and cover tape:

1. The material produced by the functional layer is formed into a film by blow molding and wound for further application. The thickness of the film is 35 μm.

2. Preparation of a 12 μm thick single-sided corona discharge treated biaxially stretched polyester film. The surface of the corona discharge treatment was coated with a polyurethane glue (35%, an adhesive available from MITSUI TAKEDA CHEMICAL, A-969V/A-5 was 3/1). The thickness of the glue after baking is about 2 μm. The resulting functional layer film was combined with the surface of the gel-coated polyester film and then cured at room temperature.

3. Dissolve 2 kg of polyacrylate copolymer (DSM) powder in 16 kg of ethyl acetate solvent with stirring, and then add 1 kg of 15% carbon black conductive solution (PC AUTO carbon black, Nippon Paint Co., Ltd., China) and 2 kg of toluene and further stirred for 5 minutes for further application. In the solution, the solid content of the acrylic resin was 9.5% and the ratio of the conductive carbon black to the acrylic resin was 1/13.3. The solution was applied to the surface of the polyester film combined with the functional layer and the obtained product was dried in an oven to remove the solvent and wound up. The acrylic resin layer is a heat-sensitive adhesive layer having a thickness of about 0.5 μm. The surface of the heat-sensitive adhesive layer has a surface resistivity of 1 × 10 ⁹ Ω / □.

4. Apply an antistatic coating solution (K104A-2, Qingdao Trade Import and Export Co., Ltd.) with a solid content of 5% on the PET surface of the heat seal film opposite to the functional layer, and bake on the oven to Used for curing. The antistatic coating has a dry film thickness of 0.2 μm and a surface resistivity of 1 × 10 ¹¹ Ω/□ under normal temperature and normal humidity.

For the obtained heat seal film, the optical transmittance is 75%, the haze value is 10%, and the surface resistivity on the surface of the heat-sensitive adhesive is 1 × 10 ⁹ ohm/□, and the surface on other surfaces The resistivity was 1 × 10 ¹¹ ohms / □. The cover tape obtained by cutting the heat-sealable film was sealed at 160 ° C using a carrier tape, and the average peeling force was 50 g and the peeling force fluctuated within a range of about 20 g. When the cover tape and the carrier tape are peeled off, the heat seal layer at the sealing position is completely retained on the carrier tape, and no functional layer remains on the carrier tape, and thus the peeling is actually between the heat seal layer and the functional layer. The interface is peeled off.

Example 4:

Preparation of functional layer materials:

60 kg of styrene-butadiene block copolymer (CHI MEI, PB-5903), 40 kg of poly(vinyl acetate) (HyunDai, VA60), and 0.4 kg of antioxidant A5 (Jinhai Albemarle, Shanghai Jinhai Albemarle Fine Chemicals Co., Ltd.) was uniformly stirred and melt-mixed at 180 ° C, and then cooled and granulated for further use.

Preparation of heat sealing film and cover tape:

1. The material obtained from the functional layer and the linear low density polyethylene LLDPE (1002-YB, Exxon Mobil) were co-extruded and formed into a film by a specific method and then wound for further application. The film has a total thickness of 35 μm, wherein the functional layer has a thickness of 12 μm and the polyethylene layer has a thickness of 23 μm.

2. Preparation of a 12 μm thick single-sided corona discharge treated biaxially stretched polyester film. The surface of the corona discharge treatment was coated with a polyurethane glue (35%, an adhesive available from MITSUI TAKEDACHEMICAL, A-969V/A-5 was 3/1). The thickness of the glue after baking is about 2 μm. The polyethylene surface of the above two-layer film was combined with the surface of the gel-coated polyester film and then cured at room temperature.

3. Dissolve 2 kg of polyacrylate copolymer (DSM) powder in 16 kg of ethyl acetate solvent with stirring, and then add 2 kg of 20% ATO solution (nano tin oxide / cerium oxide solution) and 1 kg Toluene was further stirred at high speed for 5 minutes for further application. In the solution, the acrylic resin had a solid content of 9.5% and a ratio of ATO to acrylic resin of 1/5. The solution was applied to the surface of the polyester film combined with the functional layer and the obtained product was dried in an oven to remove the solvent and wound. The acrylic resin layer is a heat-sensitive adhesive layer having a thickness of about 0.5 μm. The surface of the heat-sensitive adhesive layer has a surface resistivity of 1 × 10 ⁹ Ω / □.

4. Apply an antistatic coating solution (K104A-2, Qingdao Trade Import and Export Co., Ltd.) with a solid content of 5% on the PET surface of the heat seal film opposite to the functional layer, and bake on the oven to Used for curing. The antistatic coating has a dry film thickness of 0.2 μm and a surface resistivity of 1 × 10 ¹¹ Ω/□ under normal temperature and normal humidity.

For the obtained heat-sealing film, the optical transmittance was 85%, the haze value was 15%, and the surface resistivity on the surface of the heat-sensitive adhesive was 1 × 10 ⁹ ohm/□, and the surface on the other surface. The resistivity was 1 × 10 ¹¹ ohms / □. The cover tape obtained by cutting the heat-sealable film was sealed at 160 ° C using a carrier tape, and the average peeling force was 40 g and the peeling force fluctuated within a range of about 20 g. When the cover tape and the carrier tape are peeled off, the heat seal layer at the sealing position is completely retained on the carrier tape, and no functional layer remains on the carrier tape, and thus the peeling is actually between the heat seal layer and the functional layer. The interface is peeled off.

Comparison example 1:

Preparation of functional layer materials:

30 kg of styrene-butadiene block copolymer (CHI MEI, PB-5903), 75 kg of poly(vinyl acetate) (HyunDai, VA60), 45 kg of essential antistatic polymer (IDP: PolyNova PNC300R-M And 0.6 kg of antioxidant A5 (Jinhai Albemarle, Shanghai Jinhai Albemarle Fine Chemicals Co., Ltd.) were uniformly stirred and melt-mixed at 180 ° C, and then cooled and granulated for further use.

Preparation of heat sealing film and cover tape:

1. Preparation of a 16 μm thick single-sided corona discharge treated biaxially stretched polyester film. The surface of the corona discharge treatment was coated with a polyurethane-based undercoat layer having a thickness of about 0.2 μm, and then baked in an oven. At the same time, the polymer alloy obtained by the functional layer is melt-coated on the undercoat-coated polyester film, and then the obtained product is cooled and wound. The functional layer has a thickness of 30 μm and a surface resistivity of 1 × 10 ⁹ Ω/□.

2. 2 kg of polyacrylate copolymer (DSM, glass transition temperature of 42 ° C) powder was dissolved in 16 kg of ethyl acetate solvent with stirring, and then 2 kg of toluene was added and further stirred for 5 minutes for Further application. The solid content of the acrylic resin in the solution was 10%. The solution was applied to the surface having the functional layer and the obtained product was dried in an oven to remove the solvent and wound up. The acrylic resin layer is a heat-sensitive adhesive layer having a thickness of about 1 μm. The surface of the heat-sensitive adhesive layer has a surface resistivity of 1 × 10 ¹⁰ Ω/□.

3. Apply an antistatic coating solution (K104A-2, Qingdao Trade Import and Export Co., Ltd.) with a solid content of 5% on the PET surface of the heat seal film opposite to the functional layer, and bake on the oven to Used for curing. The antistatic coating has a dry film thickness of 0.2 μm and a surface resistivity of 1 × 10 ¹¹ Ω/□ under normal temperature and normal humidity.

For the obtained heat seal film, the optical transmittance was 85%, the haze value was 10%, and the surface resistivity on the surface of the heat-sensitive adhesive was 1 × 10 ¹⁰ Ω/□, and the surface on the other surface. The resistivity was 1 × 10 ¹¹ ohms / □. The cover tape obtained by sealing the heat-sealing film at 170 ° C using a carrier tape had an average peeling force of 50 g and a peeling force fluctuation range of about 20 g. When the cover tape and the carrier tape are peeled off, the heat seal layer at the sealing position is completely retained on the carrier tape, and a small amount of the functional layer also resides on the carrier tape, so that the peeling is substantially peeled off due to the cohesive force of the functional layer. After aging for one week at 52 ° C / 95 rh%, the average value of the peeling force and the fluctuation range of the peeling force were substantially unchanged.

Comparison example 2:

Preparation of functional layer materials:

30 kg of styrene-butadiene block copolymer (CHI MEI, PB-5903), 70 kg of poly(vinyl acetate) (HyunDai, VA60), and 0.4 kg of antioxidant A5 (Jinhai Albemarle, Shanghai Jinhai Albemarle Fine Chemicals Co., Ltd.) was uniformly stirred and melt-mixed at 180 ° C, and then cooled and granulated for further use.

Preparation of heat sealing film and cover tape:

1. The material obtained from the functional layer and the linear low density polyethylene LLDPE (I002-YB, Exxon Mobil) were co-extruded and formed into a film by a specific method and then wound for further application. The film has a total thickness of 35 μm, wherein the functional layer has a thickness of 12 μm and the polyethylene layer has a thickness of 23 μm.

2. Preparation of a 12 μm thick single-sided corona discharge treated biaxially stretched polyester film. The surface of the corona discharge treatment was coated with a polyurethane glue (35%, an adhesive available from MITSUI TAKEDA CHEMICAL, A-969V/A-5 was 3/1). The thickness of the glue after baking is about 2 μm. The polyethylene surface of the above two-layer film was combined with the surface of the gel-coated polyester film and then cured at room temperature.

3. Dissolve 2 kg of polyacrylate copolymer (DSM) powder in 16 kg of ethyl acetate solvent with stirring, and then add 2 kg of 20% ATO solution (nano tin oxide / cerium oxide solution) and 1 kg Toluene was further stirred at high speed for 5 minutes for further application. In the solution, the acrylic resin had a solid content of 9.5% and a ratio of ATO to acrylic resin of 1/5. The solution was applied to the surface of the polyester film combined with the functional layer and the obtained product was dried in an oven to remove the solvent and wound. The acrylic resin layer is a heat-sensitive adhesive layer having a thickness of about 0.5 μm. The surface of the heat-sensitive adhesive layer has a surface resistivity of 1 × 10 ⁹ Ω / □.

4. Apply an antistatic coating solution (K104A-2, Qingdao Trade Import and Export Co., Ltd.) with a solid content of 5% on the PET surface of the heat seal film opposite to the functional layer, and bake on the oven to Used for curing. The antistatic coating has a dry film thickness of 0.2 μm and a surface resistivity of 1 × 10 ¹¹ Ω/□ under normal temperature and normal humidity.

For the obtained heat-sealing film, the optical transmittance was 85%, the haze value was 15%, and the surface resistivity on the surface of the heat-sensitive adhesive was 1 × 10 ⁹ ohm/□, and the surface on the other surface. The resistivity was 1 × 10 ¹¹ ohms / □. After the cover tape obtained by cutting the heat-sealing film was cut using a carrier tape at 160 ° C, the average peeling force was less than 30 g. A too small peel force will weaken the seal between the cover tape and the carrier tape, which tends to cause the tape opening.

The results of the examples are summarized in the table below.

The data indicates that the formulation of the functional layer has an important influence on the size of the peel force. Since the interface between the peeling heat seal layer and the functional layer in the present invention is peeled off when the cover tape is peeled off, or peeling is caused by the cohesive force of the functional layer, the formulation of the base resin used for the heat seal layer is kept constant. In this case, the peeling force or cohesion of the functional layer when the heat seal layer is peeled off from the functional layer can be adjusted by changing the content of the styrene-butadiene block copolymer in the formulation for the functional layer. As can be seen from the data analysis, the peeling force at 180° can be increased by increasing the content of the styrene-butadiene block copolymer, and the fluctuation range of the peeling force is kept substantially constant. When a conductive polymer is added to the functional layer, the surface resistivity of the surface slightly changes and remains at 1 × 10 ¹² Ω/□ because the heat seal layer is extremely thin. If the glass transition temperature of the heat seal layer is appropriately increased, the anti-sticking effect of the cover tape can be improved. If an inorganic filler is added to the heat seal layer, the cover tape can provide antistatic properties and an increased anti-sticking effect, but the haze value is also increased.

1‧‧‧Antistatic coating

2‧‧‧ basal layer

3‧‧‧ functional layer

4‧‧‧Thermal adhesive layer

5‧‧‧Adhesive layer

6‧‧‧polyethylene layer

1 is a cross-sectional view of an antistatic heat seal film of the present invention; FIG. 2 is a cross-sectional view of another antistatic heat seal film of the present invention; and FIG. 3 is a cross-sectional view of another antistatic heat seal film of the present invention.

1‧‧‧Antistatic coating

2‧‧‧ basal layer

3‧‧‧ functional layer

4‧‧‧Thermal adhesive layer

Claims (32)

A heat seal film for encapsulating electronic components, comprising: a base layer; at least one intermediate layer provided on the base layer and comprising a mixture, the mixture comprising 100% by weight of the total weight of the intermediate layer : 5 wt% to 70 wt% of a vinyl acetate copolymer, wherein units derived from vinyl acetate account for more than 10 mol% of the copolymer; 20 wt% to 90 wt% of styrene-butadiene copolymer And 0 to 40% by weight of the conductive polymer; and at least one heat seal layer provided on a surface of the intermediate layer opposite to the base layer. The heat seal film of claim 1, wherein the base layer is composed of a material selected from the group consisting of biaxially stretched polyester, polyolefin or nylon. The heat seal film of claim 1, wherein the base layer has a thickness of from 10 μm to 30 μm. The heat seal film of claim 1, wherein the base layer has an optical transmittance of not less than 85% and a tensile strength of not less than 50 MPa. The heat seal film of claim 1, wherein the unit derived from vinyl acetate accounts for at least 20 mol% of the copolymer in the vinyl acetate copolymer. The heat seal film of claim 1, wherein the styrene-butadiene copolymer is a block copolymer. The heat seal film of any one of claims 1 to 6, wherein the styrene-butan In the olefin copolymer, the units derived from styrene account for more than 60 mol% of the total number of units of the copolymer. The heat seal film according to any one of claims 1 to 6, wherein the styrene-butadiene copolymer has a weight average molecular weight of 40,000 to 300,000. The heat seal film of claim 1, wherein the vinyl acetate copolymer comprises from 10% by weight to 60% by weight based on the total weight of the intermediate layer. The heat seal film of claim 1, wherein the styrene-butadiene copolymer comprises from 30% by weight to 70% by weight based on the total weight of the intermediate layer. The heat seal film of claim 1, wherein the conductive polymer comprises from 0 to 30% by weight based on the total weight of the intermediate layer. The heat seal film of claim 1, wherein the vinyl acetate copolymer is a copolymer of vinyl acetate and ethylene. The heat seal film of claim 1, wherein the conductive polymer is selected from the group consisting of polyacetylene, polypyrrole, polythiophene, polyaniline, polyether decylamine or polyester guanamine based antistatic polymerization. , or a combination thereof. The heat seal film of claim 1, wherein the intermediate layer has a thickness of from 10 μm to 50 μm. The heat seal film of claim 1, wherein the intermediate layer has a surface resistivity of from 1 × 10 ⁶ ohm/□ to 1 × 10 ¹⁴ Ω/□. The heat seal film of claim 1, wherein the intermediate layer further comprises 10% by weight to 60% by weight of polyethylene based on the total weight of the intermediate layer. The heat seal film of claim 16, wherein all of the polyethylene is present in the intermediate layer as a polyethylene sublayer. The heat seal film of claim 16, wherein the polyethylene has a weight average molecular weight of from 100,000 to 1,000,000. The heat seal film of claim 16, wherein the polyethylene has a melt index of from 1 g/10 minutes to 100 g/10 minutes. The heat seal film of claim 16, wherein the polyethylene sublayer has a thickness of from 10 μm to 30 μm. The heat seal film of claim 1 or 16, wherein the heat seal layer is composed of a material selected from the group consisting of poly(meth)acrylates or copolymers thereof. The heat seal film of claim 1 or 16, wherein the heat seal layer further comprises a conductive filler, wherein the conductive filler is present in an amount not exceeding 60% by total weight of the entire heat seal layer. The heat seal film of claim 22, wherein the heat seal layer has a thickness of from 0.01 μm to 10 μm. The heat seal film of claim 22, wherein the heat seal layer has a surface resistivity of from 1 × 10 ⁷ ohm/□ to 1 × 10 ¹² Ω/□. The heat seal film of claim 22, wherein the conductive filler is selected from the group consisting of nano oxides, carbon nanotubes, carbon powder, metal powder, or a mixture thereof. The heat seal film of claim 21, wherein the poly(meth)acrylate or poly(meth)acrylate copolymer has a glass transition temperature of from 30 °C to 90 °C. The heat seal film of claim 21, wherein the poly(meth)acrylate or poly(meth)acrylate copolymer has a heat activation temperature of at least 90 °C. The heat seal film of claim 1, further comprising an adhesive layer between the intermediate layer and the base layer. The heat seal film of claim 1, further comprising an antistatic coating on a surface of the base layer opposite the intermediate layer. The heat seal film of claim 29, wherein the dry film of the antistatic coating has a thickness of from 0.01 μm to 2 μm. The heat seal film of claim 29, wherein the antistatic coating has a surface resistivity of from 1 × 10 ⁶ ohms / □ to 1 × 10 ¹² ohms / □. A cover tape for heat-sealing to a carrier tape comprising an electronic component, the cover tape comprising: a base layer as defined in any one of claims 1 to 31; as defined in any one of claims 1 to 31 An intermediate layer disposed on the substrate layer for dissipating a charge; a heat seal layer as defined in any one of claims 1 to 31, disposed on the intermediate layer; and An optional antistatic coating as defined in any one of 31, which is located on a surface of the substrate layer opposite the intermediate layer, the cover tape having an average optical transmittance of at least 75% and no more than about 50% Optical haze and no more than about 1 x 10 ¹¹ surface resistivity; such that when the cover tape is heat sealed to the carrier tape to form an article, the cover tape and the carrier tape have an average peel strength of at least 20 gf/mm, The peel strength is reduced by no more than about 10% when the article experiences a temperature of not less than about 50 ° C and a relative humidity of not less than about 90% for at least 5 days.